1. Field of the Invention
The invention relates to the field of low observable structures for vehicles such as aircraft and, in particular, to a low observable structure that incorporates thermal protection.
2. Description of Related Art
The design of most radar absorption materials (RAM) used in stealth aircraft are classified. However, it is known that most make use of ferrite or graphite loaded into paints or composite materials. In fact, ferrite loaded paints for use on bridges and buildings are commercially available. For example, U.S. Pat. No. 5,312,678 “Camouflage Material” by F. P. McCullough, Jr., et al. and U.S. Pat. No. 5,094,907 “Electromagnetic Wave Absorbing Material” by T. Yamamura, et al. Furthermore, U.S. Pat. No. 6,461,432 “Ceramic Ram Film Coating Process” for making a ceramic RAM coating, although the formulation of the RAM is not disclosed. However, such RAM materials and structures do not have the capability to protect the underlying structure from fire.
Because of the fact that at any time aboard an aircraft carrier there are numerous aircraft on the deck loaded with ordinance, there is always a high risk of an explosion and fire. Thus it has been standard practice to coat the ordinance such as missiles and bombs with a thin heat resistant coating. This coating is designed to prevent the ordinance from exploding for a period of time sufficient for the ordinance to be removed to a safe location or dumped overboard.
Combining RAM material with a heat protecting barrier is old in the art. U.S. Pat. No. 4,084,161 “Heat Resistant Radar Absorber” by W. P. Manning, et al. does disclose a three-layer RAM substrate in combination with a foamed ceramic slab. The ceramic slab is made of blocks bonded together to provide the heat shield. The ceramic material is a mixture of Silicon tri0xide (SiO3), Zirconium Oxide (ZrO2) and Kaowool fibers. While this material may provide radar absorption as well as thermal protection, it does not lend itself for use in complex contour parts, were not only is radar absorption and heat protection required, but shaping to reduce the radar signature. It is obvious that the use of ceramic blocks bonded to a ram substrate is not suitable for use on small highly contoured ordinance such as missiles or bombs.
Thus, it is a primary object of the invention to provide a combination heat protection and reduced radar signature assembly for protecting structures.
It is another primary object of the invention to provide a combination heat protection and reduced radar signature assembly that is easily moldable to complex contours.
It is a further object of the invention to provide a combination heat protection and reduced radar signature assembly that can be molded to low observable shapes.
It is a still further object of the invention to provide a combination heat protection and reduced radar signature assembly that can be molded to low observable shapes suitable for use on missiles and bombs.